{
  "bibcode": "2017GCN.21181....1L",
  "body": "V. Lipunov, V.Kornilov, N.Tyurina, E.Gorbovskoy, D.Kuvshinov, A.V.Krylov,\nI.Gorbunov, P.Balanutsa, A.Kuznetsov, V.V.Chazov, D. Vlasenko\nLomonosov Moscow State University, Sternberg Astronomical Institut of MSU\n\nR. Rebolo, M. Serra, N. Lodieu, G. Israelian, L. Suarez-Andres\nThe Instituto de Astrofisica de Canarias\n\nD.Buckley\nSouth African Astronomical Observatory\n\n\nA. Tlatov, V.Senik, A.V. Parhomenko, D. Dormidontov\nKislovodsk Solar Station of the Pulkovo Observatory\n\nN.M.Budnev, O.Gres, O. Ershova\nIrkutsk State University\n\nA.Gabovich, V.Yurkov, Yu.Sergienko\nBlagoveschensk Educational State University, Blagoveschensk\n\nR.Podesta, C.Lopez, F. Podesta Observatorio Astronomico Felix Aguilar (OAFA),\nNational University of San Juan, Argentina\n\nH. Levato, C. Saffe\nInstituto de Ciencias Astronomicas,de la Tierra y del Espacio (ICATE),\nSan Juan, Argentina\n\nMASTER-SAAO  robotic telescope (MASTER-Net: http://observ.pereplet.ru)\nlocated in SAAO was pointed to the  GRB170531.84 25 sec after notice time\nand 99 sec after trigger time at 2017-05-31 20:09:15 UT. On our first (20s\nexposure)  set we haven`t found optical transient  within SWIFT error-box\n(ra=121.258 dec=-14.0328 r=0.05).\nThe 5-sigma upper limit has been about 15.5mag\n\n\nThe observations made on zenit distance = 84 degrees, galaxy latitude b =\n10 degree.\nThe moon (43 % bright part) is 19 degrees above the horizon. The distance\nbetween  moon and  object is 41\nThe sun  altitude  is -56.5 degree.\n\n\nMASTER-IAC robotic telescope (2x4 square degrees, MASTER-Net: \nhttp://observ.pereplet.ru)  was pointed to the  GRB170531A (Evans et al.,\nGCN #21170; Siegel et al. GCN #21172) 895 sec after notice time and 2115 \nsec after trigger time on the 2017-05-31 20:42:48 UT.\n\nThe observations were made on zenit distance = 74 degrees during \nthe twilight. The sun  altitude  was  -9.6 degree.\nThe moon (43 % bright part) is 58 degrees above the horizon. The distance \nbetween  moon and  object is 41deg.\n\nOn our 5-th (180s exposure)  set we haven`t found optical \ntransient  within SWIFT error-box (ra=121.258 dec=-14.0328 r=0.1).\nThe 5-sigma upper limit m~13.9mag (unfiltered) on the first image and\n\n\nMASTER-OAFA  robotic telescope (MASTER-Net: http://observ.pereplet.ru) \nlocated in OAFA was pointed to the  GRB170531.84 15674 sec after notice \ntime and 15751 sec after trigger time at 2017-06-01 00:30:03 UT. On our \nfirst (180s exposure)  set we haven`t found optical transient  within \nMaster error-box (ra=121.25 dec=-14.0225 r=0.1).\nThe 5-sigma upper limit has been about 18mag\nThe message may be cited.\n\n\nThe observations made on zenit distance = 63 degrees, galaxy latitude b = \n10 degree.\nThe moon (45 % bright part) is 38 degrees above the horizon. The distance \nbetween  moon and  object is 43\nThe sun  altitude  is -35.4 degree.\nThe object can be observed till 2017-06-01 02:41:37.",
  "circularId": 21181,
  "createdOn": 1496319834000,
  "email": "lipunov@xray.sai.msu.ru",
  "subject": "GRB 170531A: MASTER Net job",
  "submitter": "Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>",
  "eventId": "GRB 170531A"
}